Structure and Evolution of Low-Mass Stars: An Overview and Some Open Problems

A review is presented of some of the ingredients, assumptions and techniques that are used in the computation of the structure and evolution of low-mass stars. Emphasis is placed on several ingredients which are still subject to considerable uncertainty. An overview of the evolution of low-mass stars is also presented, from the cloud collapse phase all the way to the white dwarf cooling curve.Comment: 52 pages, 6 figures. Invited review, to appear in "XIth Special Courses at the National Observatory of Rio de Janeiro" (AIP Conf. Proc.), ed. J. Alcaniz, R. de la Reza, F. Roig, & D. F. Lope

Posição trófica de peixes exploradores de fundo na planície de inundação do Alto Rio Paraná

The δ15N composition of bottom-feeding fish (iliophagous = Apareiodon affinis, Cyphocharax nagelii, Prochilodus lineatus, Steindachnerina brevipinna and S. insculpta; detritivorous = Loricariichthys platymetopon and Liposarcus anisitsi; benthophagous = Satanoperca pappaterra and Hoplosternum littorale) and their primary food sources were investigated in the upper Paraná River floodplain during rainy seasons in different environments (lotic and lentic). Two hypotheses were tested: i) that the trophic position and isotopic values of the investigated organisms (fish and food resources) vary spatially; and ii) that trophic position and isotopic compositions differ among iliophagous, detritivorous and benthophagous fish. C4 macrophytes, periphyton and phytoplankton were isotopically different in sites analyzed. Significant isotopic differences occurred in the species of each trophic category. Spatial differences were observed in the isotopic composition of P. lineatus and L. platymetopon, whose values were more enriched in the Paraná River and Pau Véio Lake. Significant spatial differences in trophic position were observed for L. platymetopon and H. littorale, which presented the highest values in the Paraná and Baía rivers, respectively. Trophic positions were significantly different among the species that composed each trophic category. These findings demonstrate that in energy-flow studies in detrital food chains generalizations concerning the grouping of fish into trophic categories and/or habitats should only be carried out after careful investigations of the local/specific trophic dynamics of the organisms.A composição de δ15N de peixes exploradores de fundo (iliófagos = Apareiodon affinis, Cyphocharax nagelii, Prochilodus lineatus, Steindachnerina brevipinna e S. insculpta; detritívoros = Loricariichthys platymetopon e Liposarcus anisitsi; e bentófagos = Satanoperca pappaterra e Hoplosternum littorale) e suas fontes alimentares foram investigadas na planície de inundação do alto rio Paraná durante a estação de chuvas em ambientes lóticos e lênticos. Duas hipóteses foram testadas: i) que a posição trófica e os valores isotópicos dos organismos investigados (peixes e fontes alimentares) variam espacialmente; e ii) que a posição trófica e a composição isotópica diferem entre os peixes iliófagos, detritívoros e bentófagos. Macrofitas C4, perifíton e fitoplâncton foram isotopicamente diferentes entre os locais analisados. Diferenças isotópicas ocorreram entre as espécies de cada categoria trófica. Diferenças espaciais foram observadas na composição isotópica de P. lineatus e L. platymetopon, as quais tiveram valores mais enriquecidos no rio Paraná e ressaco do Pau Véio. Diferenças espaciais significativas nas posições tróficas foram verificadas para L. platymetopon e H. littorale, as quais apresentaram os maiores valores nos rios Paraná e Baía, respectivamente. As posições tróficas foram significativamente diferentes entre as espécies que compuseram cada categoria trófica. Estes resultados demonstram que em estudos de fluxo de energia em cadeias alimentares detritais generalizações a respeito do agrupamento de peixes em categorias tróficas e/ ou habitats devem ser conduzidos somente após investigações criteriosas da dinâmica trófica local/ específica dos organismos.UEM - Post-Graduate Program in the Ecology of Continental Aquatic Environment

Segregation Effects According to the Evolutionary Stage of Galaxy Groups

We study segregation phenomena in 57 groups selected from the 2PIGG catalog of galaxy groups. The sample corresponds to those systems located in areas of at least 80% redshift coverage out to 10 times the radius of the groups. The dynamical state of the galaxy systems was determined after studying their velocity distributions. We have used the Anderson-Darling test to distinguish relaxed and non-relaxed systems. This analysis indicates that 84% of groups have galaxy velocities consistent with the normal distribution, while 16% of them have more complex underlying distributions. Properties of the member galaxies are investigated taking into account this classification. Our results indicate that galaxies in Gaussian groups are significantly more evolved than galaxies in non-relaxed systems out to distances of about 4R200, presenting signficantly redder (B-R) color. We also find evidence that galaxies with M_R < -21.5 in Gaussian groups are closer to the condition of energy equipartition.Comment: 5 pages, 4 figures, accepted for publication in the MNRAS Letter

SPIDER - IV. Optical and NIR color gradients in Early-type galaxies: New Insights into Correlations with Galaxy Properties

We present an analysis of stellar population gradients in 4,546 Early-Type Galaxies with photometry in $grizYHJK$ along with optical spectroscopy. A new approach is described which utilizes color information to constrain age and metallicity gradients. Defining an effective color gradient, $\nabla_{\star}$, which incorporates all of the available color indices, we investigate how $\nabla_{\star}$ varies with galaxy mass proxies, i.e. velocity dispersion, stellar (M_star) and dynamical (M_dyn) masses, as well as age, metallicity, and alpha/Fe. ETGs with M_dyn larger than 8.5 x 10^10, M_odot have increasing age gradients and decreasing metallicity gradients wrt mass, metallicity, and enhancement. We find that velocity dispersion and alpha/Fe are the main drivers of these correlations. ETGs with 2.5 x 10^10 M_odot =< M_dyn =< 8.5 x 10^10 M_odot, show no correlation of age, metallicity, and color gradients wrt mass, although color gradients still correlate with stellar population parameters, and these correlations are independent of each other. In both mass regimes, the striking anti-correlation between color gradient and alpha-enhancement is significant at \sim 4sigma, and results from the fact that metallicity gradient decreases with alpha/Fe. This anti-correlation may reflect the fact that star formation and metallicity enrichment are regulated by the interplay between the energy input from supernovae, and the temperature and pressure of the hot X-ray gas in ETGs. For all mass ranges, positive age gradients are associated with old galaxies (>5-7 Gyr). For galaxies younger than \sim 5 Gyr, mostly at low-mass, the age gradient tends to be anti-correlated with the Age parameter, with more positive gradients at younger ages.Comment: Accepted for Publication in the Astronomical Journa

Caracteriza??o dos aspectos inflamat?rio e funcionais do ventr?culo esquerdo em c?es infectados com a cepa Berenice 78 do Trypanosoma cruzi ap?s terapia com doxiciclina e benznidazol.

Programa de P?s-Gradua??o em Ci?ncias Biol?gicas. N?cleo de Pesquisas em Ci?ncias Biol?gicas, Pr?-Reitoria de Pesquisa de P?s Gradua??o, Universidade Federal de Ouro Preto.A cardiopatia chag?sica (CC) induzida pelo Trypanosoma cruzi ? uma manifesta??o cl?nica dependente da resposta inflamat?ria gerada pelo hospedeiro, ocasionando destrui??o celular/tecidual e, consequente, remodelamento na matriz extracelular card?aca. Citocinas, quimiocinas e outras prote?nas sol?veis ou de membrana participam desta resposta imune e, por isso, estrat?gias farmacol?gicas para regular estes mediadores e desacelerar o remodelamento card?aco na CC tornam-se importantes focos de investiga??o. Na presente proposta, 30 c?es sem ra?a definida foram infectados (ou n?o) pela cepa Berenice-78 (Be-78) do T. cruzi e submetidos ao tratamento di?rio com doses sub-antimicrobial do antibi?tico doxiciclina/Dox durante 12 meses de infec??o (sendo 50mg/Kg manh? e 50mg/kg noite), em associa??o (ou n?o) com o tratamento por 60 dias com o Benznidazol/Bz (7mg/kg ? administrado ? partir do 8? m?s de infec??o), f?rmaco com a??o anti-T. cruzi. Antes e durante os 12 meses de infec??o, estes animais foram avaliados trimestralmente quanto ? fun??o card?aca (ecocardiografia/ECO) e, ap?s a eutan?sia, o tecido card?aco (?trios e ventr?culos) dos animais foram conservados para avalia??o: (i) dos aspectos histopatol?gicos (ii) da cin?tica da CCL2 plasm?tica e ventricular esquerda e da express?o dos receptores de quimiocinas (CCR3 a 6, CCR8 e CXCR3), ambos no ventr?culo esquerdo (VE). Estes par?metros foram avaliados, em paralelo ? an?lise ecocardiogr?fica. Observamos que os tratamentos reduziram a massa card?aca nos animais. A avalia??o histol?gica mostrou aumento do infiltrado inflamat?rio no VE dos animais infectados, mas Dox conseguiu reduzi-lo. A produ??o de CCL2, TNF e IFN-gama no VE foi semelhante em todos os animais infectados, mas no plasma aumentaram no 14? m?s de tratamento em rela??o ao grupo n?o infectado. Juntos, esses dados apontam para o potencial papel das doses sub-antimicrobianas de Dox, em associa??o com o Bz, como estrat?gia farmacol?gica de melhora morfofuncional card?aca associada ? infec??o pelo T. cruzi. Entretanto, novos estudos com diferentes popula??es gen?ticas do parasita e com o estudo da farmacocin?tica de Dox merecem aten??o para consolidar essa proposta.Chagasic cardiopathy (CC) induced by Trypanosoma cruzi is a clinical manifestation dependent on the inflammatory response generated by the host, causing cellular / tissue destruction and, consequently, remodeling in the cardiac extracellular matrix. Cytokines, chemokines and other soluble or membrane proteins participate in this immune response and therefore, pharmacological strategies to regulate these mediators and to reduce the advance of the cardiac remodeling in CC become important foci of investigation. In the present proposal, 30 mongrel dogs were infected (or not) with the T. cruzi, Berenice-78 (Be-78) strain, and submitted to daily treatment with sub-antimicrobial doses of the antibiotic doxycycline/Dox during 12 months of infection (50 mg/kg in morning and 50 mg/kg night), in combination (or not) with the 60 days of treatment with benznidazole / Bz (7 mg/kg administered in the 8th month of infection). Before and during the 12 months of infection, these animals were evaluated quarterly for cardiac function (echocardiography) and, after euthanasia, the blood and/or left ventricle preserved for evaluation of: (i) histopathology (ii) kinetics of plasma CCL2, (as citocinas do Alex Reis) and expression of chemokine receptors (CCR3 to 6, CCR8 and CXCR3) and (iii) MMP activities . These parameters were evaluated in parallel to the echocardiographic analysis. We observed that the treatments reduced the cardiac mass in the animals. The histological evaluation showed an increase in the inflammatory infiltration in the LV of the infected animals, but Dox was able to reduce it. The production of CCL2, TNF e IFN-gama in the LV was similar in all infected animals, but in the plasma, they increased in the 14th month of treatment in relation to the uninfected group. Together, these data point out to the potencial role of the sub-antimicrobial doses of Dox, in association with Bz, as a pharmacological strategy for cardiac morphofunctional improvement associated to the T. cruzi infection. However, new studies with different genetic populations of the parasite and with the study of pharmacokinetics of Dox deserve attention to consolidate this proposal

Biomarcadores inflamat?rios em indiv?duos adultos com sobrepeso e obesidade.

Programa de P?s-Gradua??o em Sa?de e Nutri??o. Escola de Nutri??o, Universidade Federal de Ouro Preto.A obesidade ? um grave problema de sa?de publica cuja preval?ncia vem crescendo acentuadamente nas ultimas d?cadas, inclusive em pa?ses em desenvolvimento. Trata-se de um fen?meno de transi??o nutricional precursor de doen?as cr?nico-degenerativas n?o transmiss?veis. A obesidade como condi??o inflamat?ria basal tem aberto novos horizontes para a identifica??o demarcadores inflamat?rios com utiliza??o em diagnostico ou progn?stico para as doen?as cr?nico-degenerativas. Nesse sentido, o presente estudo objetiva a quantifica??o de marcadores inflamat?rios plasm?ticos (CCL2, CCL5, CXCL16, leptina, resistina e BMP-2) correlacionando-os com marcadores cl?nicos, bioqu?micos (glicose de jejum, hemograma completo, colesterol total e fra??es, horm?nios T3, T4 e TSH) e antropom?tricos (peso, altura, circunfer?ncias corporais, pregas cut?neas e porcentagem de gordura corporal) em adultos jovens (18 a 30 anos) com sobrepeso e obesidade. Nossos resultados demostraram aumento dos par?metros antropom?tricos em indiv?duos com sobrepeso/obesidade, bem como dos n?veis plasm?ticos dos marcadores, exceto o BMP-2. Ainda, observou-se correla??o da resistina, CCL2 e CCL5 com valores de ?ndice de massa corporal e porcentagem de gordura corporal nos indiv?duos avaliados. Dessa forma, o presente estudo indica um risco potencial para os indiv?duos com sobrepeso pela similaridade nos n?veis de marcadores inflamat?rios associados ?s comorbidades associadas ? obesidade. Sugere-se, ainda, que novas investiga??es sejam realizadas objetivando um estudo de amostragem populacional para confirma??o das quimiocinas CCL5, CCL2, CXCL16 como indicadores de progn?stico clinico para comorbidades associadas ? obesidade humana.Obesity is a serious and growing world healthy problem affecting developed and in developing countries. Considered a phenomenon of the nutritional transition, the obesity is a precursor of some non-transmitted chronic degenerative diseases. The new conception of obesity as a basal inflammatory condition opens a new window of possibilities to identify inflammatory biomarkers to be used in the diagnosis or prognosis of obesity-associated comorbidities. Following this conception, this present works aim the quantification and correlation of classic (Leptin and Resistin) and new soluble markers (CCL2, CCL5, CXCL16 and BMP-2) with clinical, biochemical (fasting glucose, hemogram, cholesterol, T3, T4 and TSH) and anthropometric (weight, height, body circumferences, skinfold thickness and percentage of body fat) parameters in young adults (18 to 30 years old) presenting obesity and overweight. Our data showed increasing in anthropometric parameters in those individuals with overweight and obesity as well as in the plasma levels of inflammatory markers except to BMP-2. There was also observed correlation among CCL2, CCL5 and values of body mass index and body fat percentage in the individuals from this study. In summary, this present work proposes the existence of a potential risk to individuals with overweight due the similarity of the circulating inflammatory mediators that is commonly associated with obesity comorbidities. In addition, more investigations should be proposed, in population scale, to reinforce and define the role of the chemokines CCL2, CCL5 and CXCL16 as prognostic indicators of human obesity comorbidities

First-order decay models to describe soil C-CO2 Loss after rotary tillage

Para entendimento do impacto do preparo do solo sobre as emissões de CO2 desenvolvemos e aplicamos dois modelos conceituais que são capazes de prever a emissão de CO2 do solo após seu preparo em função da emissão da parcela sem distúrbio, acrescida de uma correção devido ao preparo. Os modelos assumem que o carbono presente na matéria orgânica lábil segue uma cinética de decaimento de primeira ordem, dada pela seguinte equação: dCsoil (t) / dt = -k Csoil (t), e que a emissão de C-CO2 é proporcional a taxa de decaimento do C no solo, onde Csolo(t) é a quantidade de carbono lábil disponível no tempo (t) e k é a constante de decaimento (tempo-1). Duas suposições foram testadas para determinação das emissões após o preparo do solo (Fp): a constante de decaimento do carbono lábil do solo (k) antes e após o preparo é igual (Modelo 1) ou desigual (Modelo 2). Conseqüentemente, a relação entre os fluxos de C das parcelas sem distúrbio (F SD) e onde o preparo do solo foi conduzido (F P) são dadas por: F P = F SD + a1 e-a2t (modelo 1) e F P = a3 F SD e-a4t (modelo 2), onde t é o tempo após o preparo. Fluxos de CO2 previstos e observados relevam um bom ajuste dos resultados com coeficiente de determinação (R²) tão alto quanto 0,91. O modelo 2 produz um ajuste ligeiramente superior quando comparado com o outro modelo. A velocidade das pás da enxada rotativa foi relacionada a um aumento na quantidade de carbono lábil e nas modificações do tempo de residência médio do carbono lábil do solo após preparo. A vantagem desta metodologia é que a variabilidade temporal das emissões induzidas pelo preparo do solo pode ser descrita a partir de uma função analítica simples, que inclui a emissão da parcela sem distúrbio e um termo exponencial modulado por parâmetros dependentes do preparo e de condições ambientais onde o experimento foi conduzido.To further understand the impact of tillage on CO2 emission, the applicability of two conceptual models was tested, which describe the CO2 emission after tillage as a function of the non-tilled emission plus a correction due to the tillage disturbance. Models assume that C in readily decomposable organic matter follows a first-order reaction kinetics equation as: dCsoil (t) / dt = -k Csoil (t), and that soil C-CO2 emission is proportional to the C decay rate in soil, where Csoil(t) is the available labile soil C (g m-2) at any time (t) and k is the decay constant (time-1). Two possible assumptions were tested to determine the tilled (F T) fluxes: the decay constants (k) of labile soil C before and after tillage are different (Model 1) or not (Model 2). Accordingly, C flux relationships between non-tilled (F NT) and tilled (F T) conditions are given by: F T = F NT + a1 e-a2t (model 1) and F T = a3 F NT e-a4t (model 2), where t is time after tillage. Predicted and observed CO2 fluxes presented good agreement based on the coefficient of determination (R² = 0.91). Model comparison revealed a slightly improved statistical fit of model 2, where all C pools are assigned with the same k constant. Rotary speed was related to increases in the amount of labile C available and to changes of the mean resident labile C pool available after tillage. This approach allows describing the temporal variability of tillage-induced emissions by a simple analytical function, including non-tilled emission plus an exponential term modulated by tillage and environmentally dependent parameters

Dark Matter and Galaxy Formation

The four lectures that I gave in the XIII Ciclo de Cursos Especiais at the National Observatory of Brazil in Rio in October 2008 were (1) a brief history of dark matter and structure formation in a LambdaCDM universe; (2) challenges to LambdaCDM on small scales: satellites, cusps, and disks; (3) data on galaxy evolution and clustering compared with simulations; and (4) semi-analytic models. These lectures, themselves summaries of much work by many people, are summarized here briefly.Comment: 37 pages, 20 figures, Lectures at XIII Special Courses at Observatorio Nacional, Rio de Janeiro, Brazil, October 2008. To appear in the Proceeding